Can body and method of forming the same



July 30, 1963 JONES 3,099,238

CAN BODY AND METHOD OF FORMING THE SAME Filed Nov. 25, 1959 INVENTOR. rMA/V z. Jam-5 United States Patent 3,99,233 CAN BGDY AND METHOD (BF FORMING THE SAME Lyman L. Jones, Kent, Wash; Alice J. Berger, executrix of said Lyman L. Tones, deceased Filed Nov. 23, 1959, Ser. No. 854,366 9 Claims. (Cl. 113-120) This invention relates to the art of making can bodies from sheet metal strips and blanks, particularly when such can bodies are blanked from a continuous roll strip or coil. It involves a new method, a new can body, and a new side seam.

The invention concerns the forming of a can body, ready for application of the normal end caps, with a novel, pressure-tight side seam which in its entirety lies the thickness of the metal blank or can body, the can body either being straight .at its ends, as in milk cans, to receive a soldered-on, flanged end cap, or having the usual outwardly directed flanges at its ends. for engagement in the usual manner with end caps that are to be seamed in place. In one aspect the invention includes a novel side seam and process of forming the can body with such side seam. Since the can body having a side seam so formed, when stressed by the usual hanging operation preparatory to applying seamed-on end caps, would tend to pull apart the side seam at its ends, and so might tend to leak, the invention includes in a coordinate aspect a novel process of fianging such a can body, and the can body as prepared for such flanging in cans of this particular type.

One object of the invention is to save so much of the metal as overlaps in the usual double-seamed side seam, which although small in individual cans, will account for large savings in the aggregate. This is done by eliminating overlapping along the side seam, utilizing only so much length of metal in the blank as is required todefine the circumferential extent of the can body.

It is a further object to eliminate from can bodies the bulge caused by the side seam, the difliculty of tightly double-seaming an end cap onto such a can body past that bulge, and the necessity for using a sealing compound required by the presence of such a bulge and the possibility of leakage there.

Also, by this invention, there remains no necessity for preserving exact registry between the blank and a lithographing mechanism, since a previously applied lithographed label even if severed within its length by blanking will still match exactly the opposite end, there being no intervening tangible side seam.

Another object is to employ dovetail interengagement between the ends of the blank, with assurance that the dovetails will interfit correctly yet without precision forming of dovetail dies, and without necessity for matching sepanate dovetail dies within very small tolerances still further, it is an object to eliect a prestretching of the metal of the inter-engaging individual dovetails, whereby their matching edges when fully engaged are finally forced strongly and pressure-tightly together. This will eliminate the need for soldering or using a sealing compound along the side seam.

Another object is to preliminarily stretch the flangeforming edges of the blank (or ends of the can body) in advance of the side-seam interengagement, whereby the so-stretched edges can be reformed as flanges after such interengagement without further stretching, thereby avoiding stress concentrated at the ends of the dovetailed side seam such as might otherwise tend to eifect separation of the dovetails, with resultant leakage. Other objects, especially those concerning details, will appear more fully hereinafter.

The invention will be illustrated in representative operations. and forms, largely diagrammatically shown, in the accompanying drawings.

FIGURE 1 is a diagram, in isometric projection of a representative process involving the steps of corrugating, blanking, flanging, roll-forming, and sideseaming a can body, according to my invention.

FIGURE 2 is an enlarged isometric view of one end of a corrugated strip, prior to but illustrating the blanking which is about to occur.

FIGURE 3 is a further enlarged isometric view of one end of a blank, illustrating the dovetails there and their stretching, FIGURE 4 is a somewhat exaggerated plan view of dovetails, and FIGURE 5 is a comparative but exaggerated end view of a single dovetail, before and after stretching, and then after flattening.

FIGURE 6 is in the nature of a side elevation, broken away, at the dovetail-forming station.

FIGURE 7 is a view similar to- FIGURE 6, but at the side seam bumping station, where the can body is completed by closing its side seam.

FIGURE 8 is an isometric view of a can body, showing the formed dovetails interengaged, but not yet bumped.

Stated briefly, according to this invention a sheet metal strip, usually supplied in coil form, is blanked into can body blanks each of the exact length to form the can body, with no excess for lapping in a side seam. If the can is to have end-seamed caps, then preferably prior to blanking, but in any event prior to interengagement of the ends of the blank, the strip is prestretched at its opposite edges, which in the blank will be the ends of the can body. This stretching may be done by corrugating such edges in a manner and in the areas to stretch those portions of the blank which will later constitute the end flanges, and to the exact extent that such portions would be stretched by flan-ging them outwardly, sothat no further stress is imposed at the side seam by the actual flanging operation, but merely a reforming of the prestressed and deformed end flange areas. If the can ends are to be straight and to receive soldered-on flanged end caps, as in milk cans, the prestretching is not required.

In blanking, each end of the strip is cut into repetitious dovetails, which later interfit perfectly because made by the same die, and regardless of imperfection v in the die initially or caused by sharpening or otherwise, after use. The blanks are then formed as can bodies, and assuming the can is to have seamed-on caps their prestretched ends are reformed as flanges, the flanging preferably preceding the can-forming. These two operation are individually similar to like operations in a normal can-making operation, except that there are no interengaging laps along the side seam, nor any attempt, as yet, to interengage the dovetailed ends.

First the individual previously blanked dovetails at both ends of the can body must be formed, either during blanking or subsequently. The forming bends each dovetail abruptly intermediate its inclined side edges, along a line parallel to the end edges of the can body, which stretches the metal and widens it, yet by drawing the side edges inwardly decreases the width of each dovetail so that they can be readily interengaged. Curving these dovetails gently will not adequately stretch them; they must be abruptly bent. The interengaged dovetails are then bumped, which flattens them and tends to further widen each one. The two widening tendencies force the inclined interengaged edges firmly together, and by reaction between the inclined edges urges their end edges firmly against the edges at the bottom of each notch. The result is a thoroughly tight joint or side seam, lying wholly within the thickness of the metal.

During the dovetail forming operation the flanges at the ends of the can body may be flattened. If so, provision is made in the bumping operation to reform the flattened flange portions.

If the caps are not to be seamed on, but merely soldered, as in milk cans, the prestretching is not necessary, for no reforming, flanging, or other stressing is required at the ends, and the dovetailed side seam remains liquidtight throughout its length.

Side seam sealing, by solder or a compound, may be effected, but is not essential, for unsoldered cans made as explained above will retain a pressure of at least thirtytwo pounds per square inch-sufficient to distort their end caps-without leakage at the side seam. It is prob able such seams will withstand much higher pressures.

A can body so formed has no tangible or bulged side seam, and every part of its and edge or end flange engages with its end cap in the normal way, equally with every other part. There i no need to allow for a bulge at the side seam ends as the side seam passes the capsealing tool, nor is there any stress developed to strain the side seam. In the non-flanged cans the cap flange fits smoothly throughout.

Two novel procedure are involved in the successful formation of can bodies by this invention. One concerns the forming and widening of the individual dovetails, and their flattening, to produce a tight side seam whether or not the caps are to be seamed onto the ends. The other is a corollary to the use of such a side seam, in a can with seamed-on caps, and concerns the prestretching, and preferably also the flanging, of the can body ends. A dovetail joint of the nature described is thoroughly tight if subject only to stress along a tangent plane at the joint and directed transversely of the joint. If, however, the metal at the ends had to be stressed by hanging the metal after the side seam was so formed, stress would be con-- centrated at the ends of the side seam, and dovetails there might pull apart, causing leakage. By prestretching, for example, by corrugating, the can body ends before closure of the side seam, the stress required to reform the ends as flanges is negligible, and does not tend to pull apart the dovetails at the ends of the can body.

Referring now to the drawings, FIGURE 1 shows diagrammatically a representative process. Roll stock from the roll R is advanced, in the flat, past blanking die members D1, D2. Here the strip S is severed into blanks B1 of a length corresponding accurately to the circumferential extent of the intended can body, with noexcess. Preferably prior to the blanking, if the can is to receive seamed-on caps, so much of the edges of the strip (the blank is itself considered as a portion of the strip) as will constitute the end flanges is corrugated or otherwise stretched, as by the oorrugating rolls C1, C2, as it passes. The stretching so efieoted is by just the amount that would be effected, in a normal can-making process, by the formation of end flanges. The corrugations are indicated at 1. Whether they depart only to one side of the plane of the blank B1, or to both sides, is immaterial. Whether or not they omit corrugations at the zone of the dovetails, a indicated by 8 in FIGURE 2, is also immaterial.

The outline of the blanking die members is illustrated in FIGURES 2 and 4, at 2. It is a dovetail form, with a narrow neck and wider outer end, and with a similarly wide bottom edge 6 within each notch. Its side edges are straight and inclined between the ends thereof. These dovetails are distributed along the length of each end of each blank B1. It may, in some instances, be considered preferable to omit a dovetail form in the flangeformi-ng portion at each end, but I prefer to continue the dovetails throughout the length of the end of the blank.

The die members D1, D2 are preferably only blanking dies, and forming dies later engage the dovetails. The purposes of forming them are two: (a) that each be stretched slightly in the direction transversely of the length of the blank B1, and (b) that each be narrowed in overall width so that they are readily interengaged with 4 like dovetails at the opposite end of the blank, in the subsequent side seam closing operation. The stretching operation is highly important :to tightness of the ultimate side seam, and forming is only incidental to ease of interengagement. Accordingly, each dovetail is bent abruptly about a median line 3, which narrows them-compare the original width at the top of FIGURE 5 with the middle width-while at the same time the abruptness of the bend along the line 3 stretches the metal somewhat,

so that actually each dovetail is wider than when it was flat, even though by a fraction of a ten-thousandth of an inch. An abrupt bend is considered essential.

The blanks '131 after blanking are advanced to flanging roll F1, F2, where each prestretched, corrugated end is flanged outwardly. Substantially simultaneously the entire blank is roll-formed, about a roll R and by the urging of a forming plate P, as is common in can-making machinery. The side seam edges are kept somewhat apart, and so related the can-body is advanced endwise by reciprocative dogs A to a dovetail forming station where dies D3, D4 (FIGURE 6) cooperate to bend each dovetail abruptly along the line 3 (FIGURES 3, 4) intermediate its sloping side edges. Magnets M1 or the like serve to maintain the can body in the correct registry with dies D3, D4, attained initially by the reciprocable advancing dogs A.

Next on the can body advances lengthwise to a bumping station. On its way the dovetailed ends are brought together, interengagingly, as by springs T, hence when bumped by the bumping bar G (FIGURES 1, 7) against the backing of horse H the formed dovetails are flattened again, again widening them slightly, and their edges are thereby urged tightly together.

The preceding overall narrowing of the dovetails by bending them, which occurs at one end at least, although preferably at both ends of the blank, makes their interengagement extremely simple. Once i-nterengaged, the bumping operation flattens all dove-tails. The flattening restores each dovetail to its initial plane, within the thickness of the blank, but it also stretches or tends to stretch each dovetail once more in the direction transverse to the length of the blank, since its flexure is now opposite to its initial forming fiexure. This causes the dovetail to assume, so much as it can in view of the restraint of the adjoining dovetails, the width 4. Since each dovetail similarly crowds adjoining dovetails, the composite action is to force the complementally inclined side edges of the dovetails together and tocause slight relative slip page in the direction circumferentially of the can body B2. This in turn urges the outer end edge 5 of one dovetail tightly against the bottom end edge 6 of the notch whereinto it fits. This makes a side seam so tight throughout that, without more, it will retain test pressures ordinarily prescribed for cans. Solder or sealing compound may, if desired, be used along the side seam as an added precaution.

The dovetail forming operation (FIGURE 6) may flatten the end flanges at the ends of the side seam. If so, the dogs W at the bumping station, acted upon by the striker V, will reform these portions of the end flanges, or their reformation can be otherwise suitably accomplished. The can body B2, with its formed dovetail interengaged, is shown in FIGURE 8, and its end flanges are flattened at 9. The latter will be struck up again at the bumping station, without imposing any appreciable stress at the ends of the side seam. The can body is then complete, ready for application of an end cap in the normal way.

Such a can body, with end caps applied in the usual manner to its flanges 7, is pressure-tight. There is no enlargement caused by the end portions of the usual double-seamed side seam, about which the end caps must be sealed tightly. Rather, all parts of the flanges, like all parts of the body, are smooth and uninterrupted, lying wholly within the thickness of the metal. This improves the seal at the ends, and lessens the cost of the can. There is no excess of metal for overlapping at the side seam, which will in the aggregate effect a material saving. End cap flanges of milk cans, which latter lack flanges, fit the smooth exterior about the entire circumferential extent of the can body. Also, since the dovetailed ends match perfectly, and are smooth, no necessity exists to maintain precise registry of the blank with lithographing mechanism; a l-ithographed label may well span a side seam of this nature.

I claim as my invention:

1. A method of forming a tube from a deformable metal strip comprising blanking the strip with a die along two spaced parallel traverse lines thereof to form the tube body blank, said die being constructed to form complemental dovetail projections and dovetail notches along the entire length of each traverse line, abruptly bending each dovetail projection along at least one of the edges of the tube body blank about a bend line extending along substantially the entire length of the longitudinal axis of the dovetail projection intermediate its axially extending edges to draw the edges toward one another and impart a V cross section to the dovetail projection while stretching and spreading the material of which it is made transverse said bend line, rolling the tube body blank into tubular form, interfitting the dovetail projections and dovetail notches on said edges of the tube body blank to form a seam, and flattening the bent and stretched dove-tail projections into the plane of the seam to effect interengagement thereof with the dovetail notches wherein they fit.

2. A method according to claim 1 further comprising deforming at least one of the end portions of the tube body blank to stretch and spread the material therein.

3. A method according to claim 2 wherein said one end portion of the tube body blank is corrugated to stretch and spread the material therein.

4. A method according to claim 2 further comprising bending said one deformed end portion out of the plane of the tube body blank to form a flange thereon.

5. A method according to claim 2 wherein said one end portion is deformed prior to the step of interfitting the dovetail projections and dovetail notches on the tube body blank edges.

6. A method according to claim 1 further comprising deforming the longitudinal edge portions of the strip to stretch and spread the material therein.

7. A method according to claim 6 wherein the longitudinal edge portions of the strip are corrugated to stretch and spread the materiai therein.

8. A method of forming a tube from a deformable metal strip comprising blanking the strip with a die along a traverse line thereof, displacing the strip and said die relative to one another until a second spaced parallel traverse line of the strip is reached, blanking the strip along said second traverse line with said die to form the tube body blank, said die being constructed to form complemental dovetail projections and dovetail notches along the entire length of each traverse line, abruptly bending each dovetail projection along at least one of the edges of the tube body blank about a bend line extending along substantially the entire length of the longitudinal axis of the dovetail projection intermediate its axially extending edges to draw the edges toward one another and impart a V cross section to the dovetail projection while stretching and spreading the material of which it is made transverse said bend line, rolling the tube body blank into tubular form, interfit-ting the dovetail projections and dovetail notches on said edges of the tube body blank to form a seam, and flattening the bent and stretched dovetail projections into the plane of the seam to eifect interengagement thereof with the dovetail notches wherein they fit.

9. A method of forming a tube from a deformable metal strip comprising blanking the strip with a die along two spaced parallel traverse iines thereof to form the tube body blank, said die being constructed to form a series of complemental dovetail projections and dovetail notches along the entire length of each traverse line, the series along one traverse line being identical with that formed along the other, abruptly bending each dovetail projection along at least one of the edges of the tube body blank about a bend line extending along substantially the entire length of the longitudinal axis of the dovetail projection intermediate its am'ally extending edges to draw the edges toward one another and impart a V cross section to the dovetail projection while stretching and spreading the material of which it is made transverse said bend line, rolling the tube body blank into tubular form, interfitting the dovetail projections and dovetail notches on said edges of the tube body blank to form a seam, and flattening the bent and stretched dovetail projections into the plane of the seam to effect interengagement thereof with the dovetail notches wherein they fit.

References Cited in the file of this patent UNITED STATES PATENTS 1,999,818 McIntyre Apr. 30, 1935 2,262,758 Erne Nov. 18, 1941 2,330,207 England et al Sept. 28, 1943 2,616,588 Hein-Ie Nov. 4, 1952 2,730,983 Campbell et al J an. 17, 1956 2,761,202 Beare Sept. 4, 1956 FOREIGN PATENTS 542,450 Great Britain Jan. 9', 1942 

1. METHOD OF FORMING A TUBE FROM A DEFORMABLE METAL STRIP COMPRISING BLANKING THE STRIP WITH A DIE ALONG TWO SPACED PARALLEL TRAVERSE LINES THEREOF TO FORM THE TUBE BODY BLANK, SAID DIE BEING CONSTRUCTED TO FORM COMPLEMENTAL DOVETAIL PROJECTIONS AND DOVETAIL NOTCHES ALONG THE ENTIRE LENGTH OF EACH TRAVERSE LINE, ABRUPTLY BENDING EACH DOVETAIL PROJECTION ALONG AT LEAST ONE OF THE EDGES OF THE TUBE BODY BLANK ABOUT A BEND LINE EXTENDING ALONG SUBSTANTIALLY THE ENTIRE LENGTH OF THE LONGITUDINAL AXIS OF THE DOVETAIL PROJECTION INTERMEDIATE ITS AXIALLY EXTENDING EDGES TO DRAW THE EDGES TOWARD ONE ANOTHER AND IMPART A V CROSS SECTION TO THE DOVETAIL PROJECTION WHILE STRETCHING AND SPREADING THE MATERIAL OF WHICH IT IS MADE TRANSVERSE SAID BEND LINE, ROLLING THE TUBE BODY BLANK INTO TUBULAR FORM, INTERFITTING THE DOVETAIL PROJECTIONS AND DOVETAIL NOTCHES ON SAID EDGES OF THE TUBE BODY BLANK TO FORM A SEAM, AND FLATTENING THE BENT AND STRETCHED DOVE-TAIL PROJECTIONS INTO THE PLANE OF THE SEAM TO EFFECT INTERENGAGEMENT THEREOF WITH THE DOVETAIL NOTCHES WHEREIN THEY FIT. 